Planetary gear transmission



Sept. 1D, 1940. A KURTl 2,214,335

PLANETARY GEAR TRANSM I S S I 0 N Filed June 25, 1938 3 Sheets-Sheet 1 Sept. l0, 1940. A. KURTI PLANETARY GEAR TRANSMISSION 'Filed June 2s, 19:58

3 Sheets-Sheet 2 9W WMM@ R. mw z s w m l m a M Sept. l0, 1940. A, KUR-n 2,214,335

PLANETARY GEAR TRANSMIS S ION m mission.

Patented lo', m40 y UNITED STATES PATENT orsi-cs mamar Gaan. .TRANSMISSION u 'maaar xura', Highland Park, N. J., miglior a, Mack Manufacturing Corporation, Longr Island 1 City, N. Y., a corporation of Delaware Appucauon June za, 193s, serial No. 215.315

This invention relates to transmissions and particularly to variable speed planetary transmissions suitable for use in vehicles and other variable speed power-operated machines.

.5 Planetary transmissions oi' various types are well known and for many years were widely used in automobiles and in many other poweroperated devices. However, this type of transmission had several disadvantages. As a con- 4l0 sequence they have been supplanted almost entirely by non-planetary transmissions.

'I'he planetary transmissions most commonly used included brake bands and brake drums which controlled the operation ofV the planel5 tary gear systems, of which there were usually several, in order to provide the desired number of speed changes. The brake bands were subject to severe wear and required replacement, thereby necessitating frequent servicing of the trans- In addition, the large number of gears in the transmission created considerable friction and reduced the efilciency of the entire system, as well as formed such complex and unwieldly constructions that repairs were diilicult to make and access to the transmission could be had only by tearing down the entire mechanism.

More recently, planetary transmissions have been devised which include electromagnetic clutches and brakes for controlling the operav tion 'of the various gear combinations. these clutches and brakes being used to replace the brake band and brake drum constructions previously used. While the electromagnetic clutches reduce the servicing requirements of the trans- .35 mission, little if any improvement was made in the accessibility of the parts or in rendering the device more compact and reducing the friction losses.

An object of the present invention, therefore, is to provide compact planetary types` of transmissions which are accessible for servicing and which are highly yeilicient in operation.

Another object of the invention is to provide planetary gear transmissions having a plurality of forward and reverse speeds in which the driving and driven elements thereof are actuated non-diilerentially in all speeds.

A further object of the invention is to provide planetary gear transmissions which can be positioned so that the driven shaft is disposed at an angle to the power shaft, thereby allowing the transmissions to be placed in substantially any desired position or location.

An additional object of the invention is t0 u provide a planetary transmission having electromagnetic clutches and brakes therein which -are supportedin such a way that they can be readily removed for adjustment and servicing and upon removal afford ready access to the gear trains of the transmission.

Other objects of the invention will become apparent from the following description of typical forms of the invention.

Planetary gear transmissions embodying the 'present invention include aligned or coaxial drive and driven shafts, the latter having a spider fixed thereto which supports the planet gears in-positlon to mesh with and transmit the torque delivered by the drive shaft by means of sun and internal gears actuated by or freed from the drive shaft by electromagnetic clutches. More particularly, the transmissions include electromagnetic clutch elements which are rotated by the drive shaft, and ilxed electromagnet brake elements which control the movement of armatures carrying sun and internal gears with which the planet gears mesh, said electromagnetic and clutch brake elements being selectively energizedto produce a plurality 'of different speed ratios. While electromagnetic clutches and brakes are used in the preferred form of transmission, it will be understood that hydraulically or pneumatically actuated clutches and the like may be used. The clutches may be of the single plate multiple disk, conical or other type, as desired.

A typical form of transmission includes a pair of annular electromagnets which are ilxed to and rotatable with the drive shaft. A clutch armature having a sun gear thereon cooperates with one of the electromagnets to couple the sun gear to the drive shaft or allow the sun gear to rotate or remain stationary. A second armature having an internal gear thereon cooperates with the other electromagnet in a similar way and in addition is controlled in its operation by means of a third electromagnetwhich is fixed to the casing of the transmission. Planet gears which are supported by a spider fixed to the driven 'shaft mesh with the sun and internal gears mentioned above. The spider also carries a second set of planet gears disposed on the side opposite to the first set'of planet gears, the two sets of planet gears being coupled to rotate simultaneously. The second set of planet gears mesh with a second sun gear and by means oi idler gears are operatively connected to an internal gear. The second mentioned sun and internal gears have armatures which cooperate with electromagnets carried by a removable end cover on the casing whereby the internal and sun gears selectively can be fixed against rotation or allowed to rotate freely.

In transmissions of this type, the various clutch and gear elements are arranged substantially symmetrically with respect to the spider, which in all speeds couples the drive shaft to the driven shaft, thereby uniformly distributing the stresses applied to the spider and greatly strengthening the entire assembly.

The spider is rotated in accordance with thev movement of the planet and idler gears along the peripheries of the, sun and internal gears. one set of planet gears being driven by a rotating gear 4or gears. 'I'he movement of the planet gears and spider are thus positive and no differential rotation of the drive and driven shaft can occur. Friction losses, therefore, are reduced for the reason that the combined planet and idler gears act substantially like the conventional idler shaft in a shiftable gear type of transmission, there being only one additional rotary component added to lthe motion of the gears; this component acting to rotate the driven shaft.

The relationship of the electromagnetic clutches, brakes, shafts, and gears to the casing of the transmission facilitates removal, repair and replacement of these parts and other servicing operations which may be required during the :s0 life of the transmission, while allowing the entire transmission to be made substantially as compact as the ordinary non-planetary transmission.

For a better understanding of the present invention, reference may be had to Ithe accompanying drawings in which:

Figure 1 is a view in horizontal section of a typical form of transmission embodying the present invention;

Figure 2 is a View in section taken on line 2--2 of Figure l; and

Figure 3 is a view in horizontal section of a modified form of transmission.

The form of the invention disclosed in Figure 1 includes a planetary transmission which can be disposed at an angle to the axis of the motor shaft and is particularly useful for rear engine vehicles and for vehicles in which the space for the engine and transmission is limited.

The device includes a housing I0 which is adapted to be connected to the crankcase of an engine (not shown), and is provided with a detachable sleeve II in which the power shaft I2 is supported for rotation in interposed roller bearings I3. The housing I0 includes a generally cylindrical casing I4 having a frusto-conical extension I5 which is detachably connected as by means of bolts I6 to a cylindrical housing I1 in which the planetary gear transmission is mount- At the left-hand end of the case I4, as viewed in Figure 1, is a sleeve I8 having roller bearings I9 therein in which is joumaled a tubular driveshaft 20. The sleeve I8 is provided with a restricted end 2l which closely yet rotatably receives the tubular shaft 20. The sleeve I8 is detachably connected to the end of the casing by means of cap screws 22 to allow removal thereof and servicing of the bearings I9. The bearings I 9 and shaft 20 are retained against relative :axial movement by a nut 23 threaded on the shaft and a shoulder 24 against which the inner race of the bearing I9 is urged by the nut 23. The tubular shaft 20 is likewise journaled in a roller bearing 25 which is detachably mounted in a partition 26 between the casing I4 and the frusto-conical housing I5. The inner race of the bearing is fixed to the shaft, 20 by a shoulder 21 on the shaft and a bevel gear 28 which is fixed to the shaft 20 by a key 29 and a nut 30 threaded on the shaft. Rotation is imparted to the shaft 20 by means of a 5 bevel gear 3| on the end of the power shaft I2 which meshes with the bevel gear 28, thus providing an angular drive between the shaft I2 and the tubular shaft 20.

'Ihe output or driven shaft 32 of this form of l0 device is disposed internally of the tubular shaft 20 and is journaled at opposite ends in anti-friction bearings 33 and 34, and in an anti-friction bearing 35 adjacent its center, the bearing 35 being mounted in a cavity 36 in the inner end 16 of the tubular shaft 20. The bearing 34 is mounted in an annular sleeve 31 which has a peripheral flange 38 engaging and detachably connected to the end cover 39 of the housing I1 by means of cap screws 40. 'Ihe end cover 39 N is pr'ovided with a flange 4I which abuts a flange 42 on the housing I1 and is connected thereto by bolts 43, thereby permitting ready removal of the end cover 39 to allow access to and servicing of the transmission.

'I'he open end of the annular bearing sleeve 31 is closed by a detachable dished cover 44 which upon removal allows the nut 45 to be adjusted on the shaft 32 to engage the inner race of the bearing 34 and urge it against the thrust disc 46 )o which bears against the shoulder 41 on the shaft 32. The outer race of the bearing 34 is retained in the sleeve 31 by means of an inwardly projecting ange 48 and a snap ring 49 which engage the opposite sides of ,the race. 35

'I'he outer race of the anti-friction bearing 33 is retained between the flanges 59 and 5I on the interiittin'g annular collars 52 and 53 respectively, which are clamped together by screws 54. 'Ihe collar 53 has a peripheral viange which abuts the 40 sleeve I8 and is held thereagainst by the bolts o1' screws 22. 'Ihe inner race of bearing 33 is xed to the shaft 32 by engagement with a flange 55 and a disc-like connecting member 56 which is keyed to the shaft 32 and urged against the race by a nut 51 threaded on a reduced extension 53 on the shaft 32.

Operation of the power shaft I2 and of the tubular shaft 20 is transmitted to the driven shaft 32 by the planetary gearing and magnetic clutch .50

and brake transmission now to be described.

The tubular shaft 20 has an enlarged inner end 59 on which is mounted in xed relation a sleeve 6D having a peripheral flange 6i. Fixed to the ange 6I and rotatable with the shaft 20 are two 55 annular electromagnets 62 and 63 provided with suitable windings 64 and 65. As illustrated, the electromagnets are formed from a casting of dished form, and are provided with at machined annular clutch faces 66 and 61. .50

'I'he sleeve 60 supports a pair of slip rings 68 and 69 which are suitably insulated from the sleeve 60 and each other, and are connected to the windings 64 and 65 of the electromagnets by means of wires passing through the conduits 10 65 and 1I in the sleeve 60 and electromagnets 62 and 63. Brushes (not shown) engage the slip rings 68 and 69 and are adapted to energize the electromagnets selectively by means of external switches.

An armature 12 forming a clutch element of 70 annular shape cooperates with the electromagnet 62 and is fixedly connected to a sleeve 'I3 which is journaled on the shaft 32 and has a sun gear 14 on its inner end. The armature 12 may rotate freely or remain stationary when the electro- 75 magnet 52 is de-energized. and rotates with the electromagnet 02 and tubular shaft 20 when the electromagnet is energized.

An armature 15 having oppositely facing plane annular faces 15 and 11 cooperates with the electromagnet 9,3 and' is xed to a dished disc 10 having a sleeve 19 at its inner edge which is rotatably mounted on the sleeve 00 projecting laterally from one end of the housing 0| in which the planet gears, later to be described. are mounted.

A third electromagnet 02, including a suitable winding 33, is nxedly mounted on an annular flange 04 which projects inwardly from the housing I1. An oil tight plug 05 is threaded into the housing |1 and a conductor 06 extends through the plug to supply electrical energy to the winding 03. By energizing the electromagnet 02 and deenergizing the electromagnet 53 the armature 15 may be restrained against movement. By energizing theelectromagnet 03 and de-energizing the electromagnet 02 the armature will rotate with the tubular shaft 20. When both of the electromagnets 03 and 02 are deenergized the armature 15 is free to rotate or to remain stationary depending upon the torque exerted on the internal ring gear 01 which is fixed to the armature 15 and the disc 10.

Meshing with the sun gear 14 and the internal gear 01 are a plurality of planet gears 00 (Figures 1 and 3) which are rotatably mounted on shafts 99 extending between and mounted in the cupshaped sides and 0| of the housing 0|. 'Ihe sides 90 and 9| of the housing 0| are connected as by means of bolts 92 to the' periphery of a disk-like spider 03 which is splined to the driven shaft 32, whereby rotation of the housing 0| and the spider 93 will cause the shaft 32 to rotate. The spider 93 has apertures 94 therein through which the shafts 09 extend.

The right-hand ends of the shafts 09 also carry planet gears 95 of smaller diameter than planet gears 00 which mesh with a sun gear 90 on the inner end of a sleeve 91 which is rotatably mounted on the shaft 32. The planet gears 00 and 95 have opposed hubs 90 and 99 provided with interiitting jaw clutch elements |00 and |0I which cause them to rotate together and facilitate assembly and disassembly of the transmission.

The side 9| of the planet gear housing 0| has a laterally projecting sleeve |02 thereon which is journaled on the sun gear sleeve 91, thereby acting with the sleeve 00 on the housing 9| and the spider 93 to form a rigid and stable construction.

'I'he planet gears 95 mesh with larger idler gears |03 which are journaled on the short shafts |04 mounted in the side 9| of the housing 0| and the spider 93. The idler gears |03 also mesh with an internal ring gear |05 which is fixed to a dished disc |05. 'I'he disc |00 has ar bearing sleeve |01 at its inner periphery which is' journaled on the sleeve |02 of the housing 0| and carries at its outer edge an armature |00 having a plane annular face |09.

The armature |00 forms with an annular electromagnet I|0 a brake for preventing or allowing free rotation of the ring gear |05. The electromagnet ||0 is fixed to the end closure 39 of the housing |,1 by means of cap screws III and is provided with a winding ||2 having a conductor passing through the oil-tight plug H3 which is threaded into the closure 39.

'Ihe sun gear sleeve 91 has a iiange ||4 'thereon to which is fixed an armature I5 having a plane annular `face ||5. 'I'he armature ||5 cooperates with an annular electromagnet ||1 to form a brake which a nxea to the end closure u by means of cap screws H0. The winding I|0 of the electromagnet ||1 is energized from an exterior source of electrical energy by means of a conductor passing through the oil-tight plug |20 threaded into the end closure 39.

It will be understood that one end of each of the windings of the electromagnets 02, 03, 02, H0 and II1 is grounded and the other is connected through suitable switches to a source of electrical energy which allow various combinations of the electromagnets to be energized.

In operation, the various speed changes may be obtained in the following way:

Assuming that the drive shaft I2 and tubul shaft 20 are rotating, a load is applied to the driven shaft 32 and none of the electromagnets are energized: the electromagnets 02 and I3 will rotate with the shaft 20 and the armatures 12 and 15 will remain stationary and no torque is transmitted to the shaft 32.

To drive the shaft 32 in first speed the electromagnets 02 and 02 are energized, thus clutching the sun gear 14 to the tubular shaft 20 and holding the internal gear 91 stationary and causing the planet gears 33 to roll around the internal gear rotating the spider 93 and the driven shaft 32 and following all the other gears to rotate freely.

In second speed, the electromagnets 03 and ||0 are energized, thus causing the internal gear 01 to rotate with the tubular shaft 20 and holding the internal gear |05 stationary with all other gears idling. The planet gears 00 are driven by the internal gears 91 causing the idler gears |03 to roll along the internal gear |05 and rotating the spider 93 and the driven shaft 32.

In third speed, the electromagnets 93 and ||1 are energized, thusv causing the 'internal gear 01 to rotate with the tubular shaft and the sun gear 95 to be held stationary. The planet gears 95 are caused to roll around the sun gear 90 rotating the spider 93 and the driven shaft 32.

In fourth speed, electromagnets 52 and 03 are energized, thereby causing the sun gear 14 and internal gear 91 to rotate with the tubular shaft 20 and locking -the planet gears 00 against rotation. The spider 93 is therefore directly coupled to tubular shaft 20 and the driven shaft 32 rotates therewith.

In first reverse speed the electromagnets 52 and ||0 are energized, causing the sun gear 14 to rotate with the tubular shaft 20 and holding the internal gear |05 stationary. The planet gears 80 and 95 and the idler gears |03 are driven vwith the idler gears |03 rolling on the fixed The construction described above is compactr and allows a, convenient arrangement and assembly of parts. For example, the use of inter- Y fitting jaw clutch elements on the planet gears allows easy assembly of parts and accurate positioning of the planetary gears relatively to each other. The use of different sizes of planet and idler gears allows very desirable ratios without any of the gears being required to rotate at excessive speeds. Also, the use of intertting parts on the planet gears and the provision of a housing which substantially enclosed the gears and which is supported rigidly on a spider, prevents end play in the gears and assures accurate meshing of the planet gears with the internal, sun and idler gears.

A very strong assembly can be produced for the reason that all of the power is transmitted through the spider directly to the driven shaft. Therefore the spider can be made of sufficient strength to handle any desired torque, and because of its central arrangement in the transmission the cooperating parts can be arranged conveniently and in closely spaced relationship thereto.

The provision of a closure member at the end of the transmission which supports two of the electromagnets allows ready access to these electromagnets for servicing and at the same time permits inspection and adjustment of the various elements of the transmission by merely removing the end closure member 39.

The provision of an angular relationship between the drive and driven shafts also allows the transmission to be used in restricted spaces and allows its positioning in the most convenient positions in the vehicle or other mechanism with which it is to be used.

In Figure 3 of the drawings is disclosed another form of the invention in which the electromagnets, their cooperating armatures, and the planetary gear system are substantially identical to the form of the invention disclosed in Figures 1 and 2. In this construction. however, the dlrive shaft 200 is in axial alignment with the driven shaft 20|,A both of these shafts being supported centrally of a substantially cylindrical housing 202 whichv is provided with outwardly directed flanges 203 by means of which it may be attached to the crank case of a motor. The drive shaft 200 includes an enlarged portion 204 on which is mounted a bushing 205 which is received within an annular collar 206. The collar 206 is bolted or otherwise attached to a transverse partition 201 in the casing 202. A bearing collar 208 is interposed between the collar 206 and the partition 201 and acts to retain a roller bearing 209 therein. The collars 206 and 208 are provided with anges which grip the outer race of the bearing 208 while the inner race of the bearing 205 is fixed to the shaft 200 by engagement between the bushing 205 -and a shoulder 2|0 on the shaft. A nut 2|| is threaded on the enlarged portion 204 of the shaft and urges the bushing 205 against the inner race of the bearing.

'I'he driven shaft 20| is provided with a reduced inner end portion 2|2 which is received within a roller bearing 2|3, the bearing being mounted in an enlarged bore 2|4 in the inner end of the shaft 200. The opposite end of the driven shaft 20| is provided with splines 2|5 which are received within a complementary internally splined sleeve 2|6 on a beveled gear 2 1. The inner races of a pair of roller bearings 2| 8 are mounted on sleeve 2|6 and are fixed thereto by means of a nut 2|! threaded on the end of the sleeve which urges the races against the beveled gear 2 I 1. The outer races of the roller bearings 2|8 are received in an annular member 220 which is bolted or otherwise fixed to an inwardly extending partition 22| on a generally frusto-conical housing 222. The housing 222 is detachably connected to the left-hand end of the casing 202 by means of bolts 223 passing through abutting flanges n.. and 225 on the housing and casing members, respectively. The beveled gear 2|1 is also provided with a bearing portion 226 at its left-hand end which is received in a roller bearing 221, the latter being mounted in a cup-shaped cap 228. The cap 228 is mounted in a circular aperture in the end of the housing 222 and is retained therein by any suitable means such as bolts 229 which pass through anges 230 and 23| on the casing 222 and cap 228, respectively. A firm and rigid support is thus provided for the driven shaft 20|.

'I'he inner end of the drive shaft 200 is provided with a disc-like flange 232 on which is mounted a disc-shaped member 233 forming the armatures of two electromagnets 234 and 235. The windings of the electromagnets 234 and 235 are connected to the commutators 236 and 231 encircling the drive shaft 200 adjacent to the flange 232. The electromagnet 234 cooperates with an armature 238 having a at annular face 239 which is connected to a disc-shaped flange 240 on the right-hand end of the sun gear 24|. The electromagnet 235 cooperates with an armature 242 which is mounted adjacent the periphery of a dished member 243 having a sleeve 244 at its inner end. Adjacent the periphery of the dished member 243 is an internal ring gear 245 which meshes with a series of planet gears 246 which are mounted in a housing 241. The housing 241 is xedly connected to a spider 248 which is connected by splines 249 to the driven shaft 20|. The housing 241 is provided with a sleeve 250 which is rotatably journaled on the sun gear 24|. The sleeve 244 of the dished member 243 is journaled on sleeve 250. The planet gears 246 mesh with the sun gear 24| and the internal ring gear 245 and are rotated in response to selective operation of the internal and sun gears to rotate the spider 248 and the driven shaft 20|.

The armature 242 also cooperates with a fixed electromagnet 25| which is connected to the casing 202 in any desired way, and acts to form a brake for either preventing or allowing free relative rotation of the armature 242.

The transmission also includes another pair of electromagnets 252 and 253. The electromagnet 253 cooperates with a rotatable armature 254 which is connected to an internal gear 255 and supported on a dished member 256 which is rotatably journaled on a sleeve 251 projecting from the left-hand side of the planetary gear housing 241. The electromagnet 252 cooperates with a rotatable armature 258 which is fixed to the outer end of a sleeve 259 having a sun gear 260 at its inner end. The sleeve 259 is rotatably mounted on the driven shaft 20| and supports rotatably the sleeve 251 on the planetary gear housing 241. Small planet gears 26| which are detachably coupled to the planet gears 246 mesh with the sun gear 260 and also with idler gears 262 which mesh with the internal ring gear 255. The idler gears are rotatably mounted on transverse shafts 263 extending between the planetary gear housing 241 and the spider 248.

'I'he combination of electromagnetic clutches, sun, planetary, and internal gears described above is substantially the same as that disclosed in Figures 2 and 3 of the drawings and is controlled in exactly the same way to obtain four forward speeds and two reverse speeds.

The operation of driven shaft 20| is taken 0E at an angle by a beveled gear 264 which meshes with the beveled gear 2|1 on the left-hand end of the driven shaft. 'I'he beveled gear 264 is provided with Oppositely directed shafts 2l! and 28B', the latter having a coupling member 2t! connected thereto by means of a key 261 and a retaining nut 288. The short shaft 265 is mounted in a ball-bearing 269 which is supported in a cup-shaped closure 210 and is retained therein by means of a snap ring 21|. The cup-shaped closure member 210 is provided with laterally directed flanges 212 which abut flanges 213 adjacent an opening in the left-hand end of a small housing 214 which is arranged at an angle to the main casing 20| and may be formed integrally with the housing 222 as by casting or by any other desired method. 'I'he shaft 265' is mounted in roller bearings 215 which are retained on the shaft 265' by engagement with the lateral face of the beveled gear 264 and by engagement of the connecting member 266 against the outer edge of the inner race of the bearing. The outer race of the bearings 215 is mounted in a sleeve 218 which has a laterally projecting flange 211 overlying and connected to the end of the housing 214 as by means of screws 218. An inner collar 219 is mounted within the sleeve 216 and hasan annular flange 280 therein which engages an edge of the outer race and retains it in abutment with the shoulder 28! on the sleeve 216. The collar 218 is attached to the sleeve 216 by means of screws 282.

'I'his construction likewise provides a simple, compact and easily accessible construction which may be readily taken down for servicing. Likewise, the angular relationship between the output end of the device and the drive end of the device permits the use of this construction in spaces which are either too small for the ordinary transmission or inconveniently situated.

It will be seen that the constructions described above provide adequate support for all of the various elements of the device, thereby resulting in reduction of friction losses, vibration and relative shifting of the various parts. and causing the gears to mesh properly and to operate without excessive wear.

Either of the devices disclosed above may be provided with force feed lubrication systems if desired, or they may be adapted to run in oil, thereby assuring adequate lubrication of all the parts of the transmission.

It will be understood that many variations can be made in the relationship, size and proportions of the parts, such as, for example, the gear ratios of the sun, planet and internal gears, to produce any desired range of transmission speeds. Such changes should be considered as being within the contemplation of the present invention as defined in the following claims.

Iclaim:

1. In a planetary transmission, the combination of a drive shaft, a driven shaft, electromagnetic clutch elements rotatable in response to rotation of the drive shaft, a rst sun gear, a iirst internal gear, armatures on said gears forming clutch elements cooperating with said electromagnet clutch elements, a ilxed electromagnetic brake element cooperating with the armature on the first internal gear, a second sun gear, a second internal gear, armatures forming brake elements on said second sun and internal gears, fixed electromagnetic brake elements cooperating with the armatures on said second internal and sun gears, a spider fixed to said drive shaft and interposed between said ilrst and second gears, said gears and shafts being coaxial and relatively rotatable, a rst planet gear rotatably mounted on said spider and meshing with said first sun and internal gears, a second planetgear fixed to said first planet gear and meshing with said second sun gear and an idler gear meshing with said second planet and internal gears, whereby upon energizing said electromagnetic clutch and brake elements selectively in pairs the drive shaft will actuate the driven shaft to produce four forward and two reverse speeds.

2. In a planetary transmission, the combination of a drive shaft, a driven shaft, clutch elements fixed to and rotatable in response to operation of the drive shaft, a first sun gear, a flrst internal gear, clutch elements on said sun and internal gears cooperating with the clutch elements on the drive shaft and effective to cause the sun gear and internal gear to rotate with said drive shaft, a fixed brake element cooperating with the clutch element on said internal gear effective to prevent rotation of the internal gear, a second sun gear, a second internal gear, brake elements on said second gears, fixed brake elements cooperating with the brake elements on said second sun and internal gears to selectively prevent rotation of said second gears, a spider fixed to said driven shaft and interposed between said first and second gears, said gears and shafts being coaxial and relatively rotatable, a rst planet gear rotatably mounted on said spider and meshing with said first sun and internal gears, a second planet gear fixed to said first gear and meshing with said second sun gear, and an idler gear meshing with said second planet and internal gears, whereby upon actuating said clutch and brake elements selectively in pairs the drive shaft will actuate the driven shaft to produceA four forward and two reverse speeds.

3. In a planetary transmission the combination of a casing having a detachable end closure, a drive shaft and a driven shaft rotatably mounted in said casing, a rst sun gear, a first internal gear, said gears being relatively rotatable and being journaled on one of said shafts, clutch elements fixed to said gears, cooperating clutch elements on said drive shaft and selectively operable to cause the said gears to rotate with the drive shaft, a brake element fixed to said casing and selectively operable to prevent rotation of the internal gear, a second sun gear, a second internal gear, brake elements on said second gears, said gears being relatively rotatable and Journaled on one of said shafts, cooperating brake elements fixed to said end closure and selectively operable to prevent rotation of said second sun and internal gears, a spider fixed to the driven shaft and interposed between said first and second gears, a first planet gear rotatably mounted on said spider and meshing with said first sun and internal gears, a second planet gear fixed to said first gear and meshing with said second sun gear, and an idler gear meshing with said second planet and internal gears, whereby upon actuating said clutch and brake elements selectively in pairs the drive shaft will actuate the driven shaft to produce four forward and two reverse speeds.

4. The planetary transmission set forth in claim 2 in which the drive shaft is tubular and the driven shaft is rotatably mounted within the drive shaft.

5. The planetary transmission set forth in claim 3 in which the clutch and brake elements fixed to the drive shaft, the casing and the end closure are electromagnets.

6. 'Ihe planetary transmission set forth in claim 2 comprising housing elements fixed to said spider, bearing sleeves extending laterally from claim 2 comprising housing elements-fixed to said said housing and affording lateral stability to spider, shafts mounted in said housing, planet said spider, and shafts mounted in said housgears rotatably mounted on and adjacent the ing in parallel relationship to said drive and drvends of each shaft, and interengaging clutch ele- 5 en shafts and rotatably supporting said planet ments on the planet gears mounted on the same 5 gears. shaft for coupling said planet gears.

7. The planetary transmission set forth in ALADAR KUR'I'I.

CERTIFICATE' oFYCoRREcTIoN. Patent No. 2,21lh555. september 1o, 191m.

- ALADAR KURTI. I It is' hereby certified that error appears the printed specification ofthe above numbered patent requiring correction as follows: Page 5, first co1umn,'1ine 72', claim l, for the word "driven read -`driven-g and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.V

signed and sealed this 8th day of october, A. D. 191m.

Henry Van' Arsdale, (Seal) Acting Commissioner of Patents. 

